London has been battered by 50mph winds that have felled trees and caused travel chaos. Powerful gusts swept across the capital as the Met Office issued a yellow "be aware" weather alert for most of the country.

You would imagine that Dev Patel, movie star and boyfriend of his ethereally beautiful Slumdog Millionaire co-star Freida Pinto, lives a very glamorous life.

But in fact the lanky, boyishly handsome 21-year-old still lives at home in Harrow with his parents. Sorry? No sleek love nest in Mumbai, New York or Soho? What?

"That's on the checklist, man," says Patel sheepishly. "It's nice living at home but I'm definitely ready to move out. If you found my house on Google maps and it had a volume button you would hear my crazy family screaming."

There were reports last year, complete with pictures, that he and Pinto, who is seven years his senior, had bought a house in Santa Monica.

"We were visiting a friend and carrying some boxes for him - suddenly we're buying this mansion," he protests. "They string together all these stories: by now we have a brood of eight children and houses all over the place. The truth is we are hungry young actors, trying to get a grip on this industry and work hard in it. So we're just bouncing wherever the work takes us."

Right. One tends to romanticise Patel's life because the storyline of Slumdog Millionaire so perfectly matches the upstart success of the 2008 film itself. No one wanted to back Danny Boyle's mad Mumbai romance starring a bit-player from Skins (Patel) and an unknown Indian model (Pinto).

But not only did the film go on to reap critical and popular acclaim, win eight Oscars and gross over £238 million worldwide, the two leads also fell secretly in love.

On screen, his character Jamal got the girl and the cash but Slumdog didn't bring Patel millions.

"It didn't make me a huge ton," he admits. "I'd just about got an agent, I was very fresh and a complete nobody. But, not wishing to sound clichéd, it did amazing things for me."

Brought up with his sister in Rayners Lane by their IT consultant father and carer mother - both Kenyan-born Hindus of Gujarati descent - Patel had barely travelled before the film. He had been to India precisely once, as a child, "didn't know central London all that well" and only got the part in Skins because his mum dragged him to an open audition.

Slumdog took him to Mumbai, then on a worldwide publicity tour and to the Academy Awards. Everyone he met was smitten by the film. "People came into the room with their eyes glazed with tears," he says. "It was my first gig so I thought, 'Maybe it's like this every time'."

He and Pinto tried to keep their romance "under locks, but it was difficult because we were doing press junkets together, playing lovers in the film - and everyone was guessing".

They were finally outed months later. "I was shooting The Last Airbender," he says. "And I pestered Paramount senseless to let me fly to Tel Aviv where she was filming. They feared for my emotional stability so they were arm-locked into letting me go. I'd never made a gesture like that - flying across the world to see a girl. And we got papped."

Worse, he'd told his mum he had a heavy shooting schedule that week and couldn't call her. So when she saw pictures of him canoodling with Pinto in Israel "she rang to say, 'And how is Philadelphia, my boy?' So embarrassing." Suddenly, there were hordes of cameramen outside his family's home: "It's terrifying to go out and know you are being watched by so many people."

Patel took the part of the villain, Zuko, in The Last Airbender to distance himself from the mania around Slumdog and to prove his versatility, but he visibly shivers when he mentions it now. M Night Shyamalan's 2010 sci-fi turkey was awful, even without the word "bender" in the title.

"On paper, it looked the most amazing project," says Patel. "It was a big CGI film. I was 18. I did martial arts for eight years [he is a black belt in tae kwondo]. But what I realised so quickly is how small you are in the process of making one of those movies. I kind of got lost in the chaos."

Worse, it didn't do much to stop him being stereotyped. He has turned down endless roles for "taxi drivers and tech geeks", and says that when he auditions in the US, casting directors are often surprised by his British accent. Several black and Asian actors have recently said the US is more welcoming than the UK.

"No. No way," Patel says. "London is much more multicultural, much more giving to minorities. My great-grandmother lives in Wembley. She can't speak English and is way past the age where she is ever going to learn, but she can get by because this place caters for that. And in terms of movies there are good Asian characters and ground-breaking dramas being written here. I can't wait to do a gritty British drama. I'll come cheap. As we've established..."

Here's the rub: Patel is only just getting the breaks. He's about to head back to LA, where he's spent three months making Aaron Sorkin's new TV drama, Newsroom, with Emily Mortimer and Jeff Daniels. He plays a young tech-savvy Asian (groan) who shot footage of the London Tube bombings and has parlayed it into a role as social media editor at a US news channel.

His most recent film, The Best Exotic Marigold Hotel, is only the third he has made, whereas Pinto has done six since Slumdog, in very varied roles. It sees him back in India playing another bright-eyed idealist, in this case a henpecked lad who decides to turn the crumbling family home into a hotel for ageing Brits, played by ageing-Brit acting royalty: Dench, Wilton, Nighy, Smith.

Patel makes a good case for wanting to work with these icons, and describes a pre-shoot dinner where everybody tried to bite the shape of different continents into poppadoms: "So, Judi was munching out Africa..." He was also genuinely enthused to have worked with director John Madden, and to have had a chance to visit India again.But even though his character is flamboyant, funny, and has a seriously hot girlfriend, it is a supporting role, and a broad one at that. It must be hard: he implies he never appreciated the quiet life until the Slumdog bandwagon rolled noisily over him, never appreciated the adulation and intense scrutiny until it went quiet again. Does he envy Pinto her success?

"No. Everyone runs their own race," he says. "She's a woman, I'm a man. Well, I'm not even a man, just a young kid. That's what I'm seen as because I've got this baby face. I won't get those big-boy roles until my facial hair fills out a bit. Being patient is hard, and keeping myself stimulated during the quiet times is a big thing. But it's been a blessing being with her. It's kept me driven, seeing her work, when I'm not working."

Do the differences in age and background affect their relationship? "It fits, the opposites just work," he says, getting flustered. "Um, er, I get awkward talking about this. She's just wonderful."

Does he go along with the prevalent opinion - that he's punching above his weight with the seriously beautiful Pinto?

"I used to hate that," he concedes, before putting on a mock-outraged tone. "She's beautiful - but what about my personality! What about what I bring? She's lucky to have me! But now my attitude has changed. If I saw this beautiful woman with a dude who looks as unfortunate as I do, the first thing that would come to my mind would be: 'You lucky bastard'."